The present invention relates to a device and a method for detecting and analyzing deposits.
Industrial plants, like power plants, steel mills, pulp or paper making plants, usually comprise means for conducting or storing fluids, e.g. pipe lines or fluid containers. It is a known issue that organic and inorganic matter deposits on the inner walls of these means for conducting or storing fluids, whereby an accumulation of fouling or scaling deposits at least partially blocks the flow through the conducting means. In this way, conducted or stored fluids may become contaminated. This is an unwanted occurrence that causes a number of operational problems such as plugging of equipment, inefficient usage of chemicals, increased utility costs, lost production due to downtime, corrosion, and downgraded products from increased dirt counts.
In principle, one can distinguish between fouling deposits on the one hand and scaling deposits on the other hand. Fouling deposits are organic deposits which often occur in the form of biofilms in aqueous systems. Such biofilms substantially consist of micro-organisms, e.g. bacteria, algae, fungi and protozoa. Contrary thereto, scale depositions occur from inorganic matter that have been identified include e.g. complexes of calcium (carbonate, oxalate, sulfate, silicates), aluminum (silicates, hydroxides, phosphates), barium sulfate, radioactive radium sulfate, and silicates of magnesium.
Industrial plants usually comprise multiple functional units, like boiler, heat exchanger, condenser, mixer, for instance. These multiple functional units are connected to each other, in particular in series and/or in parallel, via connection pipes and the like.
A problem of known devices for measuring fouling or scaling deposits in an industrial plant is that it is difficult to install such like measuring devices inside of the functional units because of e.g. limited installation space or excessively elevated temperatures inside the functional units. Consequently, the devices are provided usually at or in the connecting pipes between the functional units, even though the temperatures inside of the functional units are regularly higher than in the connecting pipes, in particular when the functional unit comprises e.g. a boiler. This is disadvantageous for the quality of the measurements because higher temperatures increase the growth of fouling, so that there is frequently a higher accumulation of deposits inside the functional units than inside of the connection pipes. Consequently, the results measured in the connecting tubes are falsified and the thickness of deposits in the relevant areas cannot be accurately determined.
In order to avoid the accumulation of fouling deposits and in particular the growth of biofilms, biocides are added into the fluid concerned as countermeasures. Scaling deposits can be removed by adding chemical deposit control agents based on homopolymers, co-polymers and terpolymers of acrylic acid, methacrylic acid, maleic acid and aspartic acid. Furthermore the chemical deposit control agents can be based on organic phosphonates and their derivatives, as well as on polyphosphates. The dosage of these biocides and chemical deposit control agents has to be accomplished very carefully and conservative because they are very expensive and pose a health hazard.